I was on the depo-provera shot for about two years &now i'm not taking it. i still haven't had a period since. how will i know if i'm ovulating?

Difficult : It's difficult to tell immediately after stopping the Depo-Provera shot especially if you haven't had a period in two years or so. One of the ways would be using your basal body temperature which isn't always the easiest to do. Generally if you give it some time your period should return and your hormones should normalize so you will be able to tell better.